title: Clinical validity of a normal perfusion lung scan in patients with suspected pulmonary embolism.
abstract: The objective of this study was to test the safety of withholding anticoagulant therapy in patients with clinically suspected pulmonary embolism who have normal perfusion lung scans, regardless of the clinical manifestations. Anticoagulant therapy was withheld or withdrawn in 515 consecutive patients except in patients in whom deep-vein thrombosis was detected. Only three of the 515 patients had symptomatic venous thromboembolism on follow-up. The frequency of symptomatic pulmonary embolism on follow-up was one of 515 patients. With knowledge of the normal findings by perfusion scanning, an alternative diagnosis was established in 367 of the 515 patients. Cause of symptoms remained uncertain in 148 patients. It is safe to withhold anticoagulant therapy in patients with suspected pulmonary embolism and normal perfusion scans, regardless of the clinical manifestations. The finding of a normal perfusion scan excludes the presence of clinically important pulmonary embolism and makes pulmonary angiography unnecessary.
authors.affiliation: Division of Internal Medicine, University of Calgary, Alberta, Canada.
authors.forename: R D
authors.initials: RD
authors.lastname: Hull
authors.forename: G E
authors.initials: GE
authors.lastname: Raskob
authors.forename: G
authors.initials: G
authors.lastname: Coates
authors.forename: A A
authors.initials: AA
authors.lastname: Panju
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010992:Plethysmography, Impedance; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000188:drug therapy; D011877:Radionuclide Imaging; D013923:Thromboembolism / Q000175:diagnosis
chemical_list: D000925:Anticoagulants